This invention relates to a roller chain, more particularly a roller chain used for conveyance.
A roller chain especially used for conveyance is commonly provided with rollers which roll on a guide or the like. Therefore, in order to accomplish smooth rolling of the rollers and to reduce the running resistance of the chain, a chain having bearing rollers disposed between the rollers and the bushing has been proposed.
In a roller chain, for example as illustrated in FIG. 7, the bearing rollers B are held at the cavity portion of the rollers A and additionally a guide ring E is placed at the gap between the end-surface of the bearing rollers B and the inner-surface of the inner link plate D.
However the rolling resistance of the rollers of such a chain can be reduced, the lateral load acting on the rollers A is transmitted to the bearing rollers B through the part F where the inside-surface of the cavity portion and the end-surface of the bearing rollers B are in contact with each other. Also, the lateral load is sustained by the link plate D. through the part G where the end-surface of the bearing rollers B and the inside-surface of the guide ring B are in contact with each other and the outside-surface of the guide ring B.
Moreover, in such a roller chain, the radial length of the parts F, G has been restricted to be not in excess of 30% of the diameter of the bearing roller B, because of the dimentional restriction of the chain. Therefore, each parts F, G is not wide enough to sustain a large lateral load. Consequently, in case that the parts F, G are worn away, the lateral play of the roller A is increased up to the total amount of each abrasion. Furthermore, for reducing the abrasion, it is necessary to lubricate the contact parts e.g. F and G. Because, the chain having the guide ring E disposed between the bearing rollers B and the inner link plate D reduces the volume of the space between the roller A and the bushing C, this results in decrease of the lubricant such as grease reserved therein, and consequent acceleration of the deterioration of the lubricant and shortening the life of the chain.